1. Field of the Invention
The invention relates to a method for drying bulk goods, in particular solids, such as granular materials, powders, grains, films, shreds, or the like, preferably plastic granular material, in a drying silo by an air flow. The exhaust air flow that is discharged from the drying silo or the returning air is dried in a drying cell, preferably a wheel dryer, that contains a drying or adsorbing agent and reintroduced to the bulk goods as drying air flow, and furthermore the adsorbent is regenerated and cooled in the wheel dryer, wherein a rotatable drum of the wheel dryer is divided into at least three wheel segments. The region of a wheel segment is used for drying or dehumidifying the exhaust air flow, the region of the second wheel segment is used for heating the adsorbent, and the region of the third wheel segment is used for cooling the adsorbent.
2. Discussion of Background Information
Various methods and devices are known for drying the returning air that exits from the drying silo.
DE 36 25 013 A1 shows one of these known methods. In the course of the known method, the exhaust air exiting from the drying funnel is dried in a dryer containing an adsorbing agent and returned to the bulk goods as drying air.
Furthermore, a method and a device for drying and heating air that serves for drying bulk goods is known from DE 197 57 537 A1. The device essentially comprises at least one drying cartridge or drying cell, a downstream air heater, a downstream dry goods chamber or drying silo and a downstream cooling device.
Furthermore, a method for regenerating humidity-laden process air is known from DE 101 18 762 A1. Thereby, the atmospheric air is heated up and introduced to the drying cartridge for regeneration. The subsequent cooling of the drying cartridge is achieved by a partial stream of air diverted from the dried process air.
A method for drying humid air is known from EP 0 712 656 B1, and a method and a device for regenerating an adsorbent, containing in particular humidity, from EP 740 956 A2.
Moreover, a device with multiple chambers for selective adsorption of molecules is known from DE 2 025 205 A1.
A device of the type explained above is known from AT 505 391 B1. In accordance with said device, the exhaust air flow is introduced to a feeding channel that is provided in the wheel dryer and connected with the adsorbent, diverted in the wheel dryer, conducted through the adsorbent and subsequently diverted again as drying air flow and removed in a discharging channel against the direction of flow in the feeding channel, and introduced to the drying silo. One disadvantage of said wheel dryer is that high pressures are necessary due to the high flow resistances resulting from the diversions.
All the abovementioned methods and apparatuses primarily have the disadvantages that the devices require a very complex design and a high consumption of energy for regenerating and drying is given in the case of said methods.